Differential gear



F. W. DAVlS.

DIFFERENTIAL GEAR. APPLICATION msn 1AN.25.191B.

1,389,580. PatentedSeptG, 1921.

2 SHEETS-SHEET i.

wad/73340 7f3/MA.

eiitial rotation of the drivin@ b FRANCIS w.

Vnirrnivaivrmr. GEAR;

l Application filed January 25, 191s.

To all (whom t may concern.' p

Be it known that I, F RANoIs citizen of the VUnited States, residing ,atuffalo, in the county of llr'ie and State of New` York, have inventedy anew and useful Improvement in Differential Gears, of which vthefollowing is a specification.

his invention relates to differential gears of the kind that areemployed inmotor vehicles between the source of lpower of the vehicleand the driving ground wheels, for the purpose of permitting theopposite wheels to turn at 'differential speeds when the vehicle ismoving in other than a straight course. On account of this possibledifferthese gears have certain disadvantages iii use when the tractionon the wheels is not the same. They tend to cause the vehicle to skidwhen one wheel loses traction and make it difficultto'get the vehicleoutof a bad place in the roadway on account of the loss of traction ofone or the other Vof the driving wheels. y

The object of the invention is toprovide efficient and practical meansfor overcoming such disadvantages in differential gears and whereby thedifferential gear will permit the limited relative rotation of thedriving ground wheels necessary for the proper operation of thevehicle,"but will resist the diHei-ential rotation thereof when one ofthe wheels losest-raction and tends toV cause an increased difference inthe 'rotation ofthe two wheels.l 4This object is attained by utilizingthe differential motion ofparts of the differential gear to pump orpropel a liquid, 'preferably the oil employed for lubricating thek gear,in such a manner that the resistance to the motion of the liquidincreases with an increase in the relative motion of said parts of thegear and therefore prevents any considerable differential motion ofthefpartsof the gear. Ink the constructions illustrated inthe pelevations thereof on drawings and hereinafter described the gear wheelsof the differential gear are housed orincased so as to cause theintermeshing gears to form'grota'ry gear pumps which draw oil from thesurrounding gear casing and force the same through restrictedpassages oropenings of suitable size tooffer resistance to any considerable flow ofoil.

he resistance Yto the fiow of oil yincreases proportionally to thesquare of the speed of I Specification ef Letters Patent.

ground wheels, `l

4is correspondingly increased.

ing a slightly modified OFFICE,

Davis, OFBUFFALO, NEW YORK.

Patented sept. 6, 1921'.

serial No'. `213,629. r

the pump gears, in accordancewith the well i known law of the flow ofliquids., Consequently, for the ordinary differential action fo ythegear, as when the vehicle is turning lcorners and in other cases `wherethe driving K rotate at only slightly `different i speeds, theresistance tothe rotation vof the gears forming the Vpumps will be verysmall becai'isev the. outlet openings will be sufficiently large toallow an almost free discliarge of the oil p at low rotative speeds.Iowever, whenk one driving wheel loses traction as' by ievolving on `aslippery or` soft surface, the speed of rotation of the diifergears`will increase and A will pump a The tial resistance vriving wheel whichhas not Thus thetend is greatly `reduced andthe the vehicle over badground i lVhile ythe lost traction. vehicle to skid ability tomoveutilization of the intermeshinggear wheels of the differential gearingias Ypumps for the oil is deemed to be the preferable way of carryingout the invention, the relative motion of parts of the differentialgearcaii be utilized through other instrumentalities 'for produc iaction. The invention is not, therefore, restricted to the usel ofthedifferential gear vwheels as rotary pumps.`

In the accompanying lFigure l is a sectional elevation of the rearaXleeof a motor vehicle provided with a differential gear embodying theinvention. l l Fig. 2 is a transverse sectional lelevation thereof online 2`2, fig.

Fig. 3 is a view showing the Adiffere'i'itial gear in end elevation, oneend of the gear casing being removed.

'vFigs 4,' 5 and 6 are transverse sectional lines 444,5*5 and` 656,"respectively, Fig. '1, showing respecytively the left hand,centralaiidright hand ,sets of the differential gears. vj. Figs. 7 and 8are fragmentary sections Figs. t and 5, showconstruction.

VAFig. 9 is a fragmentary section on `line 959, Fig. 8, and alsoshowinga portion of the differential gear casing.

similar respectivelyl to fragmentary longi tudiiialV smallv outlet n Ytorque whichgwill be transy 4initted tol the d ency of the ,8.5 ing'thedescribed hydraulic resistance yiio forming the `i0 sun gear w Theinvention is illustrated in the drawings in connection with adifferential gear of known type, in which is employed planet-v ary yspurpinions arranged with their axes parallel with the axes of thedividedjsliaft for the driving ground wheels. The invention is not,however, limited in application to differential gears of thisconstruction. A

represent the two shaft sections to the outer ends of which the drivingor ground wheels of the vehicle are secured, To the inner ends of theseshaft'sections are secured spur gear wheels B B respectively. C Crepresent a pair of planetary spur inions which are journaledparallelwith the shaft sections A A ina differential gear case D which issuitably journale'd to revolve about the shaft sections A A `and theheels B B. The planetarypinions C C mesh with each other as shown inFig. 5, and one of these pinions, C, extends to the left beyond theother pinion and meshes with the left handV sun gearl wheel B while theother pinionC projects to the right beyond the pinion C and meshes withthe other sun gear wheel B.k Three pairs of pinions C C are shownarranged symmetrically around the sun gears, but any desired number ofpairs, one or more, of these pinions may be used. The differential gearcase D carrying the planetary pinions C C is driven by suitable means,such as a worm E meshing witha yworm wheel F secured to or formed withthe gear case D. The gear case shown consists Vof oppositely arrangedsections or ends D D which are bolted or otherwise suitably secured toand connected by a ring worm wheel F. ,The pinions C C are mounted onshafts g which are supported at their ends in bearing holes in theopposite ends of the differential gear case D. This differential gearoperates in the usual well known manner, to turn the two sun wheels B B'and the shaft sections A A secured thereto in the same direction at thesame' speed or to permit a differential rotation of the shaft sections AA and the attached driving wheels.

Preferably, vthe several different sets of intermeshing gear wheels ofthe differential gearing are housed in or incased in such a manner thateach pair of gears which mesh with each other forms a rotary gear pump.The pumphousings or castings shown are formed by an inner casing art Hwhich extends around the sun whee s B B inthe differential case D andpartially inoloses the same and the inner portions of the planetarypinion and three removable caps or casing parts l which are suitablysecuredto the casing-part H, andeach inclosing the outer portion of onepair of the planetary pinions C C. The caps l and the casing part H areshown as pro- -ing against the ends of the caps v ary pinions j orificeso 0.

y gear pumps,

l and 3, inthe endsof the gear vided with perforated lugs h. adapted toreceive bolts for securing the caps in place. h ,indicates set vscrewspassing through threaded holes in the gear case D and bear- I forforcing them into and holding them in tight contact with the casing partThe casin g parts Hand I are formed with transverse partitions or wallsi i. The wall Vor partition z' extends into a circumferential groove inthe left hand pinion C and incloses the adjacent end of the right hand pand the wall or partition z" extends into a circumferential groove inthe right hand pinion C and incloses the adjacent end of the left handpinion C. rIhe H, l with the partitions irl casing parts and the ends ofthe differential gear casing D thus forma left hand pump casing orchamber K, see Fig. 4, which incloses the sun wheel yB and the left handportions of the pinions C meshing there* with, a second pumpV casing orchamber K, see Fig., (i, inclosing the other sun gear wheel B and' theright hand portions of the pinions C meshing therewith, and threeintermediate pump chambers or casings K2, see Fig. 5, each of whichincloses the intermeshing portions ofone pair of the planet- In theconstruction shown in Figs. 1-6, the pump chamber K is provided with twooil admission openings Z Z for each of the pinions C and with twodischarge or exit orifices or openings m m for each of the pinions C.Thepump chamber K is provided with similar oil admission openings Z Zand oil discharge or exit openings m m. Each of the pump chambers K? isprovided with twoV oil' admission openings n n and two oil discharge orexit Each pair of pinions with the housings thus forms three rotary ornine pumps in all, as there are three pairs of the pinions C C. In orderto insure a continuous 'supply of oil to the gear case D for the severalpumps, flanged rings or shells l? are preferably arranged on oppositeends of the gear case so as to form annular oil channels which dip intothe oil in the oil reservoir formed b the axle casing. Vhen the gearcase lg rotates the oil will be carried up in the channels 29 and willpass from the same into the gear case through suitable holes Q, Figs.

case. In the use of the there is any differential rotation between thesun wheels B and B', the pinions C ywill rotate about their own axes andthe pumps formed by the intermediate gears will draw oil in through theadmission openings Z l and wat and discharge the same through theseveral oil exit orifices m and o or 'm' andY 0', depending upon thedirection of rotation ofthe gears. For instance, ifthe differential gearwhen rotation ofthe gear wheels.

.sun -gear wheel B rotates in a vexit t clockwise direction the oil'willbedischarged through the exit orifices m and 0 and if thegear wheel'Bisrotated in an anti-clockwise direction the oil will be dischargedthrough the other exit orifices mf and 0. The resistance to thedischarge of the oil through these orifices and to the relative rotationof the pump gears will increase with an increase in the differentialrotation of the shaft A Af B', as before explained.

The construction shown in Figs. 7 to 9 is exit orificesm m and 0 o arereplaced by exit grooves. r and s kindicate respectively the inlets forthe left hand and central pumps and and u indicate the exit grooves forthe same pumps respectively. Three exit grooves t are'formed in one'endchamber inclosing the sun gearVV and an exit groove u is formed in oneend of the housing inclosing each pair of gears C C and connects withthe bearing opening for one of t exit grooves for the pumps of the righthand set are arranged similarly to those of the left hand set. In theoperation of the construction shown in Figs. 7 to 9, the oilis admittedthrough the inlets r ands and is carried around bythe p inions C C andenters the grooves t and u at one or the other end thereof,depending-upon the direction of This construction is desirable for thereason that the exit grooves are located so that the teeth of the gearssweep over them and act to clear the grooves of any foreign particles inthe oil whichmay lodge in and tend to clog the grooves, and for thereason that the connectionof kthe exit grooves with the bearingsprovides a forced feed lubrication for the bearings. Furthermore, withthe. exit groove arranged around one gear of each i `pump and the singleinlet located at the far side of the other gear of the pump, the leakageof the oil around the gears is reduced and high pressures are insured.

I claim as myinvention:` Y l. The combination with driven members, anddifferential gearwheels connecting said members for producingdifferential motion thereof, of parts cooperating with said gear wheelsto form a plurality of complete gear pumps actuated by the differentialmotion of said members to propel a liquid, whereby the resistance tosaid differential motion increases with an increase in said differentialmotion, lall of said pumps operatingto thus resist said differentialmotion in both directions of rotation of said driven members.

Vferential mechanism to form a and the attached gear ywheels B i bers topropel hese gears. The inlets and the `in rotation of said driven larotary casingk in which VIgardless of the direction ,gea-rs, and vmeans2. The combination with drivenmenibers, and..,differential mechanismconnecting said members for producing differential motion thereof, ofparts cooperating with said difcomplete pumps actuated bysaiddifferential mechanism and operating upon difference in motion of saidmembers ,to propel .liquid through restricted exits whereby said liquidresists an increase in the differential motion of said members, all ofsaid pumps operating to thus resist said differential motion invbothrdirections of rotation of said fdriven members, and means forsupplying liquid to said pumps.

3. In a differential gearing, the combination with intermeshingdifferential rotation of parts cooperating with said gears to form aplurality of complete pumps actuated by said intermesliing gears andoperatingupon a difference in rotation of said driven meinliquid throughrestricted exits, whereby said liquid resists an increase in liquid toall of said pumps in the several different positions thereof.

, 4. In a differential gearing, the combination with intermeshing gearsfor producing dierential rotation of driven members, of partsyassociated with said plurality of pumps actuated by said intermeshinggears and operating upon adiiference members to propel liquid throughrestricted exits, whereby said liquid resists an increase in thediffer-k ential rotation of said driven members, `and said differentialmechanism is located and to and from which said pumps take and returnthe liquid, and means for supplying liquid to the several pumps'in thedifferent positions ing. t

5. In a differential gearing, the combination with intermeshing gearsfor producing differential motion of two rotary members, of a pumpchamber inclosing intermeshing gears and providing liquid inlets andrestricted liquid exits and forming with said gears a rotary gear pump,said inlets and exits being disposed to cause similar resisted pumpingaction of said pump reof rotation of said for supplying liquid to saidpump. f 6. In a 4differential gearing, the combination withinterineshing gears for `producing differential motion of two rotarymembers, of a pump chamber inclosing a pair of said intermeshing gearsand forming with said gears a rotary said lcasing `having provision forthe inlet and restricted exit of liquid when the gears rotate in onedirecplurality ofl gears for producingy driven members, of`

of said casa pair of said gears to form a liquid when the gears rotatein the opposite direction, and means for supplying liquid to said pump.

7 In a differential gearing, the combination with. interme'shing gearsfor producing differential motion of driven members, of a pump chamberinclosing a pair of said intermeshing gears and providing a liquid inletand a liquid exit 'and formingv with said gears a rotary gear pump, andmeans for continuously supplying liquid for said pump in the severaldifferent positions thereof, said exit being proportioned so that saidliquid resists an increase in relative rotation of said intermeshinggears.

8. In a differential gearing, the'combination with intermeshing gearsfor producing differential motion of driven members, of a pump chamberinclosing a pair of said intermeshing gears and provi ing a liquidinletand a liquid exit and forming with said gears a rotary gear pump, andmeans for continuously supplying liquid for said pump in the severaldifferent positions thereof, said exit being proportioned so as topermit a relatively free discharge of the liquid at low relativerotations of said intermeshing gears and to resist the discharge of theliquid and oppose increased relative rotation of said intermeshinggears.

9. In a differential gearing-the combina-v tion with intermeshing gearsfor producing differential motion of driven members, of a pump chamberinclosing a pair of said intermeshing gears and providing Aa liquidinlet and a liquid exit and forming with said gears a rotary gear pump,a liquid reservoir from which said pump draws the liquid, and means forcontinuously supplying liquid from said reservoir to said pumps in theseveral different positions thereof, said exit being proportioned so asto increase the resistance to the movement of the liquid by the pumpwith an increase in the relative rotation of said intermeshi g gears.

10. In a differential gearing, the combination with pairs ofinterineshing gears for producing differential motion of driven members,of pump chambers inclosing the several pairs of intermeshing gears andproviding liquid inlets and liquid exits and forming with said pairs ofgears rotary gear pumps, means for continuously supplying liquid forsaid pumps in the several different positions thereof, said exits beingproportioned so that said liquid resists'an increase in relativerotation of said interme'shing gears.

1l. In a differential gearing, nation with intermeshing gears ingdifferential rotation of of a pump actuated by said intermeshing 'thecombifor produc- 'case having an openi liquid from gear case.

theliquid in said reservoir `ing aliquid inlet and having a nIVitnes'ses: driven members,

,gears and' operating upon a difference in rotation of said drivenmembers to propel liquid through a restricted exit, whereby said liquidresists an increase in the Vdifferential rotation of saidy drivenmembers, a gear case for said differential mechanism which rotatestherewith, a liquid reservoir in which said gear case rotates, said gear`ng therein to admit the reservoir into the gear case, and means forcausing a continuous admission of liquid from said reservoir into sai12. In a nation with intermeshing gears for producing differentialrotation of driven members, of a pump actuated by said intermeshing jgears and operating upon a difference in rotationA of said drivenmembers to propel liquid ythrough aA restricted exit, whereby saidliquid resists an increase in the differential rotation of said drivenmembers, a gear case for said differential mechanism which rotatestherewith, a liquid reservoir in which said gear case rotates, and anannular liquid channel on said gear case which dips into for receivingthe liquid, said gear case having an opening therein to admit liquidfrom said channel into the gear case.

13. In a differential gearing, Vthe combination with intermes'hing gearsfor Vproducing differential motion of driven members, o a pump chamberinclosing a pair of said intermeshing gears, said pump chamber having aliquid inlet and having a liquid 'exit 'groove and forming with saidgears a rotary gear pump, said exit groove being located said pump. Y

la. In al differential gearing, the combination with intermeshing Ygearsfor producing 'differential motion of driven members, of a pump chamberinclosing a pair of said intermeshing gears, said pump chamber havliquidexit groove and forming with said gears a rotary gear pump, said exitgroove being located so that it is swept by `the teeth ofl one of saidgears and being connected with a bearing opening for said differentialgearing whereby the liquid is discharged through said bearing opening,and means for supplying liquid for said pump.

differential gearing, the combifitness my hand this 22nd day of J anuivary, 1918.`

FRANCIS W. DAVIS.

LM. J. PrrMAN, C., W. PARKER.,

l It is hereby certified that in Letters Patent No. 1,389,580, grantedSeptember 6, 1921, upon the application of Francis W. Davis, of Bulalo,New York, for an improvement in Differential Gears, an error appears inthe printed specification requiring correction as follows: Page 3, line130, claim 6, before the Word exit insert the Word restricted,` and thatthe said Letters Patent should be read with this lcorrection thereinthat the same may conform to the record of the case in the Patent Olice.

Signed and sealed this 18th day of October, A. D., 1921.

[SEAL] i KARL rENNrNe,

Acting Commissioner of Patents.

Correction in Letters Patent No. 1,389,580.

